Fix memory leaks in the FT font engine

The glyph returned by loadGlpyh() must be freed manually when caching
is not enabled (that is, QT_USE_FT_CACHE is not set).

This change and https://codereview.qt-project.org/#change,65672
together should stop QGLWidget::renderText() from leaking memory
extensively.

Task-number: QTBUG-32792
Change-Id: Iff7e1591a1ea994a97b6a56bc16c64bf544e6713
Reviewed-by: Lars Knoll <lars.knoll@digia.com>
Reviewed-by: Konstantin Ritt <ritt.ks@gmail.com>

1 files changed, 18 insertions, 2 deletions

diff --git a/src/gui/text/qfontengine_ft.cpp b/src/gui/text/qfontengine_ft.cpp
index 61f4781e3f..328931e1eb 100644
--- a/src/gui/text/qfontengine_ft.cpp
+++ b/src/gui/text/qfontengine_ft.cpp
@@ -1583,6 +1583,8 @@ void QFontEngineFT::recalcAdvances(QGlyphLayout *glyphs, QFontEngine::ShaperFlag
             g = loadGlyph(cacheEnabled ? &defaultGlyphSet : 0, glyphs->glyphs[i], 0, Format_None, true);
             glyphs->advances_x[i] = design ? QFixed::fromFixed(face->glyph->linearHoriAdvance >> 10)
                                            : QFixed::fromFixed(face->glyph->metrics.horiAdvance).round();
+            if (!cacheEnabled)
+                delete g;
         }
         glyphs->advances_y[i] = 0;
     }
@@ -1621,6 +1623,8 @@ glyph_metrics_t QFontEngineFT::boundingBox(const QGlyphLayout &glyphs)
             xmax = qMax(xmax, x + g->width);
             ymax = qMax(ymax, y + g->height);
             overall.xoff += g->advance;
+            if (!cacheEnabled)
+                delete g;
         } else {
             int left  = FLOOR(face->glyph->metrics.horiBearingX);
             int right = CEIL(face->glyph->metrics.horiBearingX + face->glyph->metrics.width);
@@ -1662,6 +1666,8 @@ glyph_metrics_t QFontEngineFT::boundingBox(glyph_t glyph)
         overall.xoff = g->advance;
         if (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
             overall.xoff = overall.xoff.round();
+        if (!cacheEnabled)
+            delete g;
     } else {
         int left  = FLOOR(face->glyph->metrics.horiBearingX);
         int right = CEIL(face->glyph->metrics.horiBearingX + face->glyph->metrics.width);
@@ -1751,6 +1757,8 @@ glyph_metrics_t QFontEngineFT::alphaMapBoundingBox(glyph_t glyph, QFixed subPixe
         overall.width = g->width;
         overall.height = g->height;
         overall.xoff = g->advance;
+        if (!glyphSet)
+            delete g;
     } else {
         int left  = FLOOR(face->glyph->metrics.horiBearingX);
         int right = CEIL(face->glyph->metrics.horiBearingX + face->glyph->metrics.width);
@@ -1799,6 +1807,7 @@ QImage *QFontEngineFT::lockedAlphaMapForGlyph(glyph_t glyphIndex, QFixed subPixe
     };
 
     QFontEngineFT::Glyph *glyph;
+    QScopedPointer<QFontEngineFT::Glyph> glyphGuard;
     if (cacheEnabled) {
         QFontEngineFT::QGlyphSet *gset = &defaultGlyphSet;
         QFontEngine::HintStyle hintStyle = default_hint_style;
@@ -1834,6 +1843,7 @@ QImage *QFontEngineFT::lockedAlphaMapForGlyph(glyph_t glyphIndex, QFixed subPixe
         FT_Set_Transform(freetype->face, &m, 0);
         freetype->matrix = m;
         glyph = loadGlyph(0, glyphIndex, subPixelPosition, neededFormat);
+        glyphGuard.reset(glyph);
     }
 
     if (glyph == 0 || glyph->data == 0 || glyph->width == 0 || glyph->height == 0) {
@@ -1861,6 +1871,8 @@ QImage *QFontEngineFT::lockedAlphaMapForGlyph(glyph_t glyphIndex, QFixed subPixe
         *offset = QPoint(glyph->x, -glyph->y);
 
     currentlyLockedAlphaMap = QImage(glyph->data, glyph->width, glyph->height, pitch, format);
+    if (!glyphGuard.isNull())
+        currentlyLockedAlphaMap = currentlyLockedAlphaMap.copy();
     Q_ASSERT(!currentlyLockedAlphaMap.isNull());
 
     QImageData *data = currentlyLockedAlphaMap.data_ptr();
@@ -1886,7 +1898,9 @@ QImage QFontEngineFT::alphaMapForGlyph(glyph_t g, QFixed subPixelPosition)
 {
     lockFace();
 
-    Glyph *glyph = loadGlyphFor(g, subPixelPosition, antialias ? Format_A8 : Format_Mono);
+    QScopedPointer<Glyph> glyph(loadGlyphFor(g, subPixelPosition, antialias ? Format_A8 : Format_Mono));
+    if (cacheEnabled)
+        glyph.take();
     if (!glyph || !glyph->data) {
         unlockFace();
         return QFontEngine::alphaMapForGlyph(g);
@@ -1923,7 +1937,9 @@ QImage QFontEngineFT::alphaRGBMapForGlyph(glyph_t g, QFixed subPixelPosition, co
 
     lockFace();
 
-    Glyph *glyph = loadGlyphFor(g, subPixelPosition, Format_A32);
+    QScopedPointer<Glyph> glyph(loadGlyphFor(g, subPixelPosition, Format_A32));
+    if (cacheEnabled)
+        glyph.take();
     if (!glyph || !glyph->data) {
         unlockFace();
         return QFontEngine::alphaRGBMapForGlyph(g, subPixelPosition, t);